Normal map bake result for humanoid mesh projects arms on torso
Bias in Baking settings means how far away (in blender units) from the surface the geometry will be captured onto the baked texture. 

If the value is too high that may cause capturing additional information that is perpendicular to the surface within the set Bias.

To fix that problem you can zoom into the model and use the grid to estimate the distance to avoid capturing unwanted detais.